Synethesis Of High Temperature Drilling Fluid Additives With NVP And Its Engineering Application For Ultra-deep Well

With the rapid growth of China's national economy,the demand for oil and natural gas increases year by year,and the import of oil and gas increases greatly.Oil and gas resources have become a strategic issue affecting national energy security.At present,Daqing Oilfield has entered the middle and later stage of oilfield development,and the oil and gas resources in the middle and shallow layers are increasingly exhausted.The exploration and development of the deep traditional oil and gas resources,as well as unconventional oil and gas resources such as shale gas,tight gas and tight oil,has become one of the important alternative resources for the oil field to increase reserves.However,due to the high temperature,complex lithology,high content of clay minerals,poor cementation,microfracture/fracture development,and a large number of fracture zones in the deep stratum,such accidents as sloughing,collapse and malignant leakage occur easily in the process of drilling.Drilling is the foundation of oil and gas field development,and drilling fluid is important for ensuring safe drilling construction.Drilling fluid is especially important in deep drilling construction.The most prominent problem of deep well drilling fluid is temperature resistance.At present,high temperature resistance chemical materials used in deep well drilling fluid are always imported.Therefore,it is of great theoretical and practical significance to study high temperature resistance chemical materials and further develop drilling fluid system with excellent performance.The drilling fluid commonly used in deep drilling is mainly composed of oil-base drilling fluid and water-base drilling fluid,while the core material in oil-base drilling fluid is a high-temperature emulsifier and the core material of water-base drilling fluid is a high-temperature inhibitor.In this thesis,two kinds of core materials in drilling fluid system were made,their molecular structures were designed,and two kinds of new anti-high temperature materials were synthesized.Its molecular structure and properties were characterized by infrared spectroscopy,thermogravimetry,nuclear magnetic resonance(NMR)and liquid-mass(liquid-mass)tests.The new oil-base drilling fluid and water-base drilling fluid systems with high temperature resistance were further studied.The two kinds of drilling fluid systems have been commercially applied in the oil field.The new oil-base drilling fluid core material-emulsifier was synthesized by using monomers such as N,N-dimethyl-1,3 propylene amine and epoxy chloropropane.Research shows that the new ternary copolymer emulsifier synthesized has multiple adsorption groups and can improve the surface activity;the molecules,with special molecular structure,can gather or overlap each other to form space net structure to tighten the interfacial film and enhance its mechanical strength;the introduction of five-member ring structure monomer improves the high temperature stability,the resulting emulsion droplets under high temperature are more even and dense,which effectively solves the disadvantage of stability and thixotropy of traditional emulsifier at high temperature.The n-vinylpyrrolidone(NVP)monomers were introduced into the diethylene glycol molecular structure.A novel anti-high temperature polyamine inhibitor for the core material of water-based drilling fluid containing NVP was synthesized by three-step method.The effect of synthesis conditions for the new inhibitors on the conversion rate of products was studied.The new inhibitors synthesized contain more amine groups,and the protective group n-vinylpyrrolidone monomer introduced on the main chain increases the steric hindrance and improves the high temperature stability of the material.A new 0.5% inhibitor was added to sodium bentonite suspension,and the layer spacing was reduced from 1.932 nm to 1.418 nm,preventing water molecules from entering the clay crystal layer and inhibiting and blocking the collapse.With the new ternary copolymer as the core material,organic soil,modified asphalt,filter loss agent and other drilling fluid materials were optimized through orthogonal experiment.Experiment shows that after 16 hours hot rolling at a temperature of 260?,the demulsification voltage remains above 500 v,and the drainage volume is only 0.5 mL.This indicates that the system has low viscosity,high shear strength,and good resistance to high temperature.The mechanism of low viscosity,high shear and high thixotropy of the system is explained by the theory of honeycomb structure.In the application process of 144 wells in Daqing Oilfield,the system showed good rheological property and filtration property,demulsifying voltage > 1500 V,dynamic and plastic ratio > 0.4,and stable performance.This effectively solved the problems such as high temperature of deep horizontal wells,easy formation of cuttings bed,poor well wall stability,etc.,and met the drilling requirements of deep horizontal wells.A synthesized anti-high temperature polyamine inhibitor was used as the core material to optimize the collapse-preventing and plugging agent and flow pattern regulator in the drilling fluid system.A water-base drilling fluid system was made,which can resist a temperature of 200 ? and has good performance in collapse-preventing and plugging.The inhibition mechanism of the water-base drilling fluid system with new anti-high temperature polyamine inhibitor is in line with the “hydrophobic field theory” about strong inhibition.The drilling fluid system was successfully applied in 580 wells in Daqing,Xinjiang and overseas oil fields,with the average length of horizontal interval of 1522 m and the longest horizontal interval of 2033 m.Simulation device for evaluating the plugging effect of micro fractures was designed,considering the deep strata lithology of Daqing Oilfield: the majority of the fractures are structural fractures and dissolution fractures,fracture density mainly is concentrated in the range of 1 ~ 5 pieces/ m,and fracture length is smaller,in the range of 2 ~ 5 m/m2.The model of aluminosilicate micro-fracture core was made;an evaluation method for simulating micro-crack sealing is established.Simulating fractures range between 1 to 200 microns wide,the highest working temperature is 200?,and pressure is between 3.5 ~ 5.0 MPa.The plugging evaluation method is applied to the developed new oil-base drilling fluid and high-performance water-base drilling fluid.The drilling fluids have a strong plugging ability for the fractured and micro-fractured strata,and the cutting-carrying effect is good.No well leakage,drilling tool sticking and high friction have occurred during the construction.These indicate that the drilling fluid systems with NVP high temperature additive can meet the drilling requirements of the deep horizontal intervals.